1. Field
Apparatuses and methods consistent with exemplary embodiments relate to acquiring distance information, and more particularly to acquiring a three-dimensional (3D) image to obtain the distance information.
2. Description of the Related Art
Recently, the importance of three-dimensional (3D) content has been magnified together with development and increasing demands of a 3D display apparatus capable of displaying an image having depth. In this regard, a 3D image acquiring apparatus, such as a 3D camera, for a general user to personally manufacture 3D content is being studied. Such a 3D camera may obtain depth information together with existing 2D color image information through a one-time image capture.
Depth information about a distance between surfaces of a subject and a 3D camera may be obtained by using a binocular stereo vision method using two cameras or a triangulation using a structure light and a camera. However, when such methods are used, accuracy of the depth information rapidly decreases when the distance increases and it is difficult to obtain precise depth information since the methods depend upon a surface state of the subject.
In this regard, time-of-flight (TOF) has been introduced. TOF is a method of emitting a light onto a subject and then measuring a time it takes for the light to be reflected at the subject and received by a light-receiving unit. According to TOF, a series of light processing operations are performed to acquire depth information. For example, a light having a certain wavelength (e.g., a near-infrared ray of 850 nm) is projected onto a subject by using an illumination optical system including a light-emitting diode (LED) or a laser diode (LD), the light reflected from the subject and having the same wavelength is received by a light-receiving unit, and then the received light is modulated by using a modulator having a known gain waveform. Various TOFs may be determined according to such a series of light processing operations.